Yes it has a barrel nut. Typical ar10 configuration. Could cast and measure but I’m too lazy, besides shooting/accuracy is the bottom line and I got lucky. Tried Sierra 168, 169, and 175s with 3 different powders and all shot very well. Chamber/freebore seems tight which is good as I’ll be using mag length cartridges.Probably several as 308 Win is a SAAMI cartridge. But when you mention DPMS LR-308, you're talking about a semi-auto barrel that uses a barrel nut, right? I have never met anyone that reams those barrels.